Imbibition is an important mechanism for enhancing oil recovery in tight reservoirs. Both nanoparticles and nanobubbles can penetrate nanoscale pores to modify oil-water properties. Furthermore，nanobubbles can additionally provide microscopic energy supplementation，making them ideal systems for permeability enhancement and recovery improvement in tight reservoirs. Taking core samples from the Chang-6 reservoir in Wuqi area as research subjects， this study investigated the permeability-enhancing characteristics of active nanofluid（nanobubbles + nano-SiO₂ particles）and simulated field application effects. The results showed that 0.1% active nanofluid enhanced core water wettability by 48.3% and reduced oil-water interfacial tension by 17.8%，which significantly decreased flow resistance and facilitated imbibition. Synergistic effects between nanoparticles and nanobubbles enhanced imbibition efficiency. The imbibition recovery of 0.1% active nanofluid was 5.47 percentage points higher than that of formation water and 2.37 percentage points superior to pure SiO₂ nanofluid. The effectiveness of the system containing nanobubbles increased by 1.76 times compared to pure nano-SiO₂ system. Differential pore mobilization mechanisms were observed between oil-wet and water-wet formations. Oil-wet reservoirs primarily mobilized crude oil from medium pores （27.8 nm＜r≤203.9 nm），while water-wet formations predominantly target large pores （r≥126.9 nm）. Simulation results indicated significant operational improvements within 3 years of active nanofluid injection，reducing water cut from 60% to 40%and achieving up to 150% daily production increase compared with non-enhanced recovery scenarios. Over a 6-year simulation period，the adjusted recovery factor surpassed conventional waterflooding by 15%. These findings provided valuable insights for imbibition recovery in tight and shale ultra-low permeability reservoirs.